Did you have it in 4th gear with clutch out when you rolled it forwards 12-18 inches before pushing in the clutch and trying the starter again?

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69 142S Overdrive + 69 164S Manual

Let me suggest checking the level of the battery acid. If one cell is too low, you will be down to 9V and that is not enough to excite the starter and you will get a clicking noise. If the battery is old, it is also possible that the sludge on the bottom slides to the down hill end and shorts out the cell. Moving the car a foot and stopping can cause the sludge to move and give you proper cell charge.


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My back feels better when I sit in a Volvo seat

J;

In general terms, having all clean and tight connections as Al suggests is not a bad thing, but more specifically, the question you need to answer is: Is the Solenoid getting power when you depress that Start Button, and working as it should?

I suggest you have a helper push Start Button as you listen under the hood for the solenoid CLACK (Out of gear, Handbrake applied!)...if no CLACK and Starter turning occurs, check for 12V at Solenoid term 50 when button is pushed...if not present, Starter Button and associated connections are suspect.

If 12V is present, but Solenoid does not CLACK, or only clicks and Starter does not turn, Solenoid is either sluggish or High Current Contacts (HCC) are carbonized and not making good connection to route power to Starter.

See: http://www.sw-em.com/starter.htm

Good Hunting!

Dirty electrical connections can cause the symptoms you're having.

Start with cleaning your terminals and connections at both ends of the battery cables. Get them nice and shiny before reinstalling and use some kind of paste (zinc based is supposed to be one of the best) on said connections.

Clean the body-to-engine block ground wire.

How old is the battery?

I think the upslope position may just be coincidental.